The present invention relates to manufacturing technology of a semiconductor device and particularly relates to technology effectively applied to a method of manufacturing a semiconductor device having a step of dividing a semiconductor wafer so as to obtain a plurality of semiconductor chips.
Japanese Patent Application Laid-Open Publication No. 2008-34875 (Patent Document 1) describes forming a curved surface on the edge of the rear surface side of a semiconductor chip. According to above-mentioned Patent Document 1, when the curved surface is formed on the edge on the rear surface side, concentration of stress onto the edge can be suppressed, and bending strength of the semiconductor chip can be enhanced.
For reducing the thickness of and advancing the functions of a semiconductor device, there are demands for the reduction in the thickness of semiconductor chips mounted on the semiconductor device. In recent years, for example, the technique of manufacturing a semiconductor chip having a thickness of 50 μm or less is required.
However, according to the studies of the inventor of the present application, it has been found out that, when the thickness of the semiconductor chip is reduced, a problem that the strength of the semiconductor chip (bending strength or shock resistance strength) is reduced occurs. A crushed layer (miniaturized crack layer of aim-order or less) formed on a rear surface or a side surface of the semiconductor chip due to external force upon processing of a semiconductor wafer in a step of manufacturing the semiconductor device serves as one of main causes that causes reduction in the strength of the semiconductor chip. This crushed layer is formed, for example, on the rear surface (ground surface) of the semiconductor wafer in a step of grinding the rear surface of the semiconductor wafer. The crushed layer is also formed on the side surface (cut surface) of the semiconductor chip in a step of dividing the semiconductor wafer. It has been elucidated that, when the crushed layer formed in this manner on the rear surface or the side surface of the semiconductor chip in the step of manufacturing the semiconductor device is remaining, the crushed layer serves as a cause of damaging the semiconductor chip in the environment of usage. It has been found out that the influence of reduction in the strength due to the crushed layer is large particularly in a thin semiconductor chip.